Acute febrile illness in children represent about 20% of visits to pediatricians and are a powerful challenge to a mother's ability to respond to distress in her child. These illness represent an opportunity to strengthen bonds between mothers and children, to advance physicians' under standing of clinical judgment and to improve the use of health care resources. The proposed study integrates child development and clinical judgment methodologies. It seeks to demonstrate that the mother-well child interaction will predict the mother-ill child interaction. Both interactions will be correlated with the reliability, specificity and sensitivity of mother;s and pediatricians, judgment during illness, with test ordering by pediatricians and with subsequent use of medical resources. It will further demonstrate that maternal, infant and social milieu characteristics are associated with both the mother-well and mother-ill child interaction and hence with clinical judgment, test ordering and utilization of resources. The study will enroll 300 children: 100 at each a hospital Health Center, an urban and suburban private practice. The mother-well child interaction will be assessed by the primary pediatrician and a Research Associate at 2 weeks, 6, 15 and 24 months by a global rating system (Emotional Availability Scales, EAS) and, on a subsample, the method of Bornstein. All acute illness over the next 30 months of life (proposed N=1000) will be assessed by tandem independent scoring of the Acute Illness Observation Scales by mother and pediatricians; from this scoring, the reliability, specificity and sensitivity of judgments will be calculated. The mother-ill child interacts on of a subsample of patients will be assessed using the EAS and the method of Bornstein. Data about test ordering and use of resource during the illness will be gathered by interview and by review of medical records. Maternal, infant and social milieu characteristics will be assessed at 2 weeks, 6, 15 and 24 months using the Beck Depression Inventory, the Parenting Sense of Competence Scale, the Rothbart, the Patenting Social Support Index and the Caldwell Home Scales. Documenting hypothesized relationships will advance our understanding of the phenomenologic basis of interpreting distress in children and of clinical judgment during acute illness. Such understanding will result in more reliable judgments with higher specificity and, hence, more apposite use of medical resources.